Abstract: A liquid-friction coupling comprises a liquid-containing housing, a shaft, which coaxially protrudes into the housing, and the interdigitating sets of inner and outer blades, which are axially slidably mounted on the shaft and in the housing, respectively, and are non-rotatably connected thereto. Annular spreading springs are disposed between adjacent inner blades or adjacent outer blades. The distance between adjacent inner and outer blades can be changed by means of an annular piston, which is operable from the outside of the housing. To permit control of the liquid friction coupling within wide limits, the annular piston has a planar inner end face, which extends close to the blades and substantially throughout the cross-section of the interior of the housing. When the piston is in its outermost position the liquid contained in the housing is not in excess of 60% of the liquid capacity of the housing. The liquid has a viscosity of at least 30,000 centistokes.

Abstract: An all-wheel driven motor vehicle capable of operating in an understeering or an oversteering condition comprises a front axle, a rear axle, and an interaxle differential comprising a planetary gear system, a releasable coupling, and a liquid friction coupling. The planetary gear system includes an input member connected to the motor of the vehicle, a first output member connected to the front axle, and a second output member connected to the rear axle. The releasable coupling interconnects the first and second output members. The liquid friction coupling is disposed between the first output member and the front axle. The three-torque transmitting members of the planetary gear system are selected so that when the releasable coupling is disengaged, the vehicle operates in an understeering condition under normal running conditions.

Abstract: An interaxle differential for connection between two driven axles (14) of a motor vehicle comprises a liquid friction coupling (1) and a planetary gear train (15) comprising three torque-transmitting members (16, 18, 20). The liquid friction coupling (1) comprises a liquid-filled housing, a coupling shaft, which coaxially protrudes into said housing at least one set of radially inwardly extending, axially spaced apart outer blades, which are mounted on the housing, and radially outwardly extending, axially spaced apart inner blades, which are fixed to the shaft in said housing and axially staggered from the outer blades. Each of said outer blades is adjustable in a radial plane to vary the radial overlap between the outer and inner blades. A first of said torque-transmitting members of the planetary gear train is directly connected to an input member of the differential gear. A second (20) of said torque-transmitting members is connected to said coupling shaft (3).

Abstract: A drive system for motor vehicles having driven front and rear axles comprises a liquid friction coupling, which is incorporated in the rear axle drive train, and a clutch, particularly an overrunning clutch, which is connected in series with said liquid friction coupling and arranged to be released in response to a front axle speed exceeding the rear axle speed. In order to avoid a requirement for stronger steering forces during a reverse travel and to avoid an operation of the liquid friction coupling with mixed friction, that second clutch is arranged to be automatically engaged in dependence on the liquid temperature in the liquid friction coupling or of other variables.

Abstract: A motor vehicle comprises two driven axles (5, 8), which are interconnected by an interaxle coupling (10) for transmitting a torque only when the halves of the coupling (10) rotate at different speeds and by a speed-changing transmission (9) connected in series with the coupling (10). A brake system (12 to 15) is provided for braking the wheels of both axles (5, 8). In order to ensure that the wheels of the driven rear axle (8) will not block before the wheels of the driven front axle (5), a pressure-setting controller (17) is adapted to control a brake pressure regulator (16) associated with the driven rear axle (8) and is responsive to a reversal of the direction in which torque is transmitted to and from the driven rear axle (8).

Abstract: In a drive system for motor vehicles having two drive axles, one of said driven axles is driven by means comprising a liquid friction coupling. In order to permit the use of a relatively small liquid friction coupling and to permit the interdependence of the speed difference between the coupling halves of the liquid friction coupling and the torque transmission capacity to be modulated within a large range with simple means, one coupling half of the preferably controllable liquid friction coupling is held against rotation, the other coupling half is connected to one torque-transmitting member of a planetary gear train having three torque-transmitting members, another of said three torque-transmitting members is arranged to be driven by the motor, and the third of said torque-transmitting members is connected to the axles to drive the same.

Abstract: A transmission unit particularly intended for use as a differential between driven axles of a vehicle comprises an epicyclic gear train having three rotatable members, specifically, an input member connected to an input shaft, a second member connected to one section of a liquid friction coupling, and an output member connected to an output shaft. To avoid an occurrence of constraining torques as the vehicle is steered and to permit a modulation within a wide range of the relationship between the speed difference between the sections of the coupling and the torque limit of the transmission unit, the second section of the liquid friction coupling is non-rotatably connected to a stationary structure of the transmission unit, specifically to a housing of the epicyclic gear train. Alternatively, said second section of the coupling may be adapted to be held against rotation by a brake, so that the axles of the vehicles can easily be uncoupled from each other.

Abstract: An interaxle differential system connecting two driven axles of a motor vehicle comprises a restrainable differential and a planetary gear train, which comprises three torque-transmitting members which have parallel axes. Two of said torque-transmitting members are operatively connected to two output shafts of the differential. A restraining device is connected to the third of said torque-transmitting members. In an interaxle differential system for use in a passenger car, the restraining device is a controllable liquid friction coupling, one coupling half of which is held against rotation.

Abstract: A drive mechanism for motor vehicles having two drive axles is disclosed. The drive mechanism includes a transmission drive followed by a differential gear unit. The differential gear unit includes first and second driven members. The first driven member is drivingly connected to the first drive axle and, via a spur gear drive system, to a first set of friction plates in a fluid friction clutch unit. The second driven member is drivingly connected to the second drive axle and, also via a spur gear drive system, to a second set of friction plates in a fluid friction clutch unit. The first set of plates and the second set of plates of the clutch unit are frictionally coupled to each other and thus act to equalize the rotational speeds of the two drive axles.To enhance the operation of the drive mechanism, the spur gear drive system connecting the driven members to the clutch unit provides a gear ratio greater than one.

Abstract: A drive system for motor vehicles having a motor which has an axis that is transverse to the direction of travel of the vehicle comprises either a manually operable change-speed transmission which is disposed substantially beside the motor, or an automatic change-speed transmission which is coaxial to the drive shafts of the front axle. The change-speed transmission is operatively connected to the front axle differential of the vehicle, optionally via idler gears, and is operatively connected by an angle drive to a shaft which leads to and is operatively connected to the rear axle.

Abstract: In a drive system for automobiles having two driven axles, a differential gearing between the axles serves at the same time as distributor gearing. A fluid friction clutch is associated with the differential gearing as an optional differential lock thereof. In order to guarantee that the distribution of the driving torques to the two axles can be changed either arbitrarily by hand or automatically on the basis of various operational data, each of the two parts of the fluid friction clutch, adapted for being coupled with each other, is driven from one of two output members of the differential gearing. A preferably continuously adjustable change-speed gearing is associated with one of the two output members. At least one piston drive for acting upon the change-speed gearing and a control unit lodged in an actuating line for the piston drive, as well as a governor for processing operational data of the vehicle or the engine thereof can also be provided.

Abstract: A four wheel drive gear box having a planetary internal differential concentric with a reduction gear driven by an output gear of a transmission, a planetary carrier driven by the reduction gear, a ring gear driving a first shaft concentric with the reduction gear, a sun gear driving a second shaft which carries a gear which drives, via other gearing, an inter-wheel differential, the first shaft driving the other inter-wheel differential, a support member enclosing the inter-axle differential and connected with the reduction gear, and a connecting member between the ring gear and the first shaft.